419 research outputs found
New families of interpolating type IIB backgrounds
We construct new families of interpolating two-parameter solutions of type
IIB supergravity. These correspond to D3-D5 systems on non-compact
six-dimensional manifolds which are T^2 fibrations over Eguchi-Hanson and
multi-center Taub-NUT spaces, respectively. One end of the interpolation
corresponds to a solution with only D5 branes and vanishing NS three-form flux.
A topology changing transition occurs at the other end, where the internal
space becomes a direct product of the four-dimensional surface and the
two-torus and the complexified NS-RR three-form flux becomes imaginary
self-dual. Depending on the choice of the connections on the torus fibre, the
interpolating family has either N=2 or N=1 supersymmetry. In the N=2 case it
can be shown that the solutions are regular.Comment: 20 page
AdS Vacua, Attractor Mechanism and Generalized Geometries
We consider flux vacua attractor equations in type IIA string theory
compactified on generalized geometries with orientifold projections. The
four-dimensional N=1 superpotential in this compactification can be written as
the sum of the Ramond-Ramond superpotential and a term described by
(non)geometric flux charges. We exhibit a simple model in which supersymmetric
AdS and Minkowski solutions are classified by means of discriminants of the two
superpotentials. We further study various configurations without Ramond-Ramond
flux charges. In this case we find supersymmetric AdS vacua both in the case of
compactifications on generalized geometries with SU(3) x SU(3) structures and
on manifolds with an SU(3)-structure without nongeometric flux charges. In the
latter case, we have to introduce correction terms into the prepotential in
order to realize consistent vacua.Comment: 35 pages, accepted version in JHE
Heterotic type IIA duality with fluxes - towards the complete story
In this paper we study the heterotic type IIA duality when fluxes are turned
on. We show that many of the known fluxes are dual to each other and claim that
certain fluxes on the heterotic side require that the type IIA picture is
lifted to M or even F-theory compactifications with geometric fluxes.Comment: 31 pages, references adde
On the Existence of Meta-stable Vacua in Klebanov-Strassler
We solve for the complete space of linearized deformations of the
Klebanov-Strassler background consistent with the symmetries preserved by a
stack of anti-D3 branes smeared on the of the deformed conifold. We find
that the only solution whose UV physics is consistent with that of a
perturbation produced by anti-D3 branes must have a singularity in the
infrared, coming from NS and RR three-form field strengths whose energy density
diverges. If this singularity is admissible, our solution describes the
backreaction of the anti-D3 branes, and is thus likely to be dual to the
conjectured metastable vacuum in the Klebanov-Strassler field theory. If this
singularity is not admissible, then our analysis strongly suggests that anti-D3
branes do not give rise to metastable Klebanov-Strassler vacua, which would
have dramatic consequences for some string theory constructions of de Sitter
space. Key to this result is a simple, universal form for the force on a probe
D3-brane in our ansatz.Comment: 35 pages, LaTeX. v2: further details provided regarding the IR
singularity and the discussion modified accordingly. typos corrected, refs
adde
No-scale supersymmetry breaking vacua and soft terms with torsion
We analyze the conditions to have no-scale supersymmetry breaking solutions
of type IIA and IIB supergravity compactified on manifolds of SU(3)-structure.
The supersymmetry is spontaneously broken by the intrinsic torsion of the
internal space. For type IIB orientifolds with O9 and O5-planes the mass of the
gravitino is governed by the torsion class W_1, and the breaking is mediated
through F-terms associated to descendants of the original N=2 hypermultiplets.
For type IIA orientifolds with O6-planes we find two families of solutions,
depending on whether the breaking is mediated exclusively by hypermultiplets or
by a mixture of hypermultiplets and vector multiplets, the latter case
corresponding to a class of Scherk-Schwarz compactifications not dual to any
geometric IIB setup. We compute the geometrically induced mu-terms for D5, D6
and D9-branes on twisted tori, and discuss the patterns of soft-terms which
arise for pure moduli mediation in each type of breaking. As for D3 and
D7-branes in presence of 3-form fluxes, the effective scalar potential turns
out to possess interesting phenomenological properties.Comment: 44 pages; several minor corrections and added reference
Hypermoduli Stabilization, Flux Attractors, and Generating Functions
We study stabilization of hypermoduli with emphasis on the effects of
generalized fluxes. We find a class of no-scale vacua described by ISD
conditions even in the presence of geometric flux. The associated flux
attractor equations can be integrated by a generating function with the
property that the hypermoduli are determined by a simple extremization
principle. We work out several orbifold examples where all vector moduli and
many hypermoduli are stabilized, with VEVs given explicitly in terms of fluxes.Comment: 45 pages, no figures; Version submitted to JHE
Heterotic Flux Attractors
We find attractor equations describing moduli stabilization for heterotic
compactifications with generic SU(3)-structure. Complex structure and K\"ahler
moduli are treated on equal footing by using SU(3)xSU(3)-structure at
intermediate steps. All independent vacuum data, including VEVs of the
stabilized moduli, is encoded in a pair of generating functions that depend on
fluxes alone. We work out an explicit example that illustrates our methods.Comment: 37 pages, references and clarifications adde
T-duality and closed string non-commutative (doubled) geometry
We provide some evidence that closed string coordinates will become
non-commutative turning on H-field flux background in closed string
compactifications. This is in analogy to open string non-commutativity on the
world volume of D-branes with B- and F-field background. The class of
3-dimensional backgrounds we are studying are twisted tori (fibrations of a
2-torus over a circle) and the their T-dual H-field, 3-form flux backgrounds
(T-folds). The spatial non-commutativity arises due to the non-trivial
monodromies of the toroidal Kahler resp. complex structure moduli fields, when
going around the closed string along the circle direction. In addition we study
closed string non-commutativity in the context of doubled geometry, where we
argue that in general a non-commutative closed string background is T-dual to a
commutative closed string background and vice versa. Finally, in analogy to
open string boundary conditions, we also argue that closed string momentum and
winding modes define in some sense D-branes in closed string doubled geometry.Comment: 31 pages, references added, extended version contains new sections
3.3., 3.4 and
Reformulating Supersymmetry with a Generalized Dolbeault Operator
The conditions for N=1 supersymmetry in type II supergravity have been
previously reformulated in terms of generalized complex geometry. We improve
that reformulation so as to completely eliminate the remaining explicit
dependence on the metric. Doing so involves a natural generalization of the
Dolbeault operator. As an application, we present some general arguments about
supersymmetric moduli. In particular, a subset of them are then classified by a
certain cohomology. We also argue that the Dolbeault reformulation should make
it easier to find existence theorems for the N=1 equations.Comment: 30 pages, no figures. v2: minor correction
Towards mirror symmetry \`a la SYZ for generalized Calabi-Yau manifolds
Fibrations of flux backgrounds by supersymmetric cycles are investigated. For
an internal six-manifold M with static SU(2) structure and mirror \hat{M}, it
is argued that the product M x \hat{M} is doubly fibered by supersymmetric
three-tori, with both sets of fibers transverse to M and \hat{M}. The mirror
map is then realized by T-dualizing the fibers. Mirror-symmetric properties of
the fluxes, both geometric and non-geometric, are shown to agree with previous
conjectures based on the requirement of mirror symmetry for Killing
prepotentials. The fibers are conjectured to be destabilized by fluxes on
generic SU(3)xSU(3) backgrounds, though they may survive at type-jumping
points. T-dualizing the surviving fibers ensures the exchange of pure spinors
under mirror symmetry.Comment: 30 pages, 3 figures, LaTeX; v2: references adde
- ā¦